The Siam Cement Group of Bangkok borrowed EUR$12\mathrm{.}5$ million for one year on February $14,2020,$ short$-$term financing provided by a European customer. The interest rate was a low $6\mathrm{.}5\%.$ The problem, however, was that the exchange rate between the Thai baht $($THB$)$ and the euro $($EUR$)$ changed from THB$33\mathrm{.}86=$EUR$1\mathrm{.}00$ on February $14,2020$ to THB$36\mathrm{.}327=$EUR$1\mathrm{.}00$ on February $16,2021,$ when the loan repayment was due. In the end, what was the interest rate paid by Siam Cement in its own currency, Thai baht?